This invention relates to an improved chain, especially to a chain used on a bicycle.
Typically, a multi-geared bicycle has a plurality of sprocket wheels and a gear cluster connected by a chain and controlled by a derailleur. On a modern bicycle there may be up to three sprocket wheels and a gear cluster with up to seven gears to obtain get a possible 21 different gear ratios to suit different road conditions.
Referring to the prior art of FIG. 9, when a rider shifts up, i.e., shifting to a higher gear ratio, a chain with a space A defined by two inner chain plates or a space B defined by two outer chain plates is received by a tooth 10 of a smaller diameter sprocket; or shifts down, i.e., shifting to a lower gear ratio, the chain is received on a sprocket with a larger diameter from one of a smaller diameter, suiting different road conditions, such as flat or hilly. A conventional derailleur cooperating with a traditional chain does not allow the rider to shift quickly. Referring to FIG. 12, it is found that while the rider is shifting, a top surface 40 of the tooth of the sprocket abuts a lateral face 30 of the chain plate; thus, the sprocket can not insert immediately into the space of the chain, delaying the rider since he has to continuously pedal to make the sprocket engage with the chain.
In addition, since the distance between two inner chain plates is shorter than that between two outer chain plates, referring to FIG. 11, while in a highest gear ratio the chain 30 is oblique to sprockets 201 and 101, thus when the sprocket inserts a tooth into a space between two inner chain plates, it is possible (referring FIG. 10), that the top surface of the tooth of the sprocket will rest on an upper face 60 of a central portion of the inner chain plate, resulting in the chain skidding from the sprocket in a direction as shown by arrow F.
It is the purpose of this present invention, therefore, to mitigate and/or obviate the above-mentioned drawback in the manner set forth in the detailed description of the preferred embodiment.